Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux-Dushman method applied to a stirred vessel

This work studies how deeply the reagents choice influences micromixing characterisation by the Villermaux-Dushman method, when applying it to a 1 L stainless steel standard vessel with two baffles, stirred by an inclined blade turbine. For the first time, borate and phosphate buffer are compared on their use in the method. It is observed that triiodide production is higher when borate buffer is used. Moreover, perchloric acid leads to higher triiodide production than sulphuric acid, when injecting the same concentration of both acids. Finally, the influence of the ionic strength is also studied, since there has been a great deal of controversy about it over the last years. The results show that the ionic strength affects triiodide production, although relatively slightly. Advice concerning the choice of the reagents is given in conclusion. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.